Bed for a coordinate measuring machine

Abstract

A bed for a measuring machine constituted by a frame provided with a pair of mutually parallel beams bearing guides for the mobile unit of the machine, and a workpiece table housed between the beams; the workpiece table and the frame are constrained to one another by constraint means that decouple the deformations thereof, and the frame comprises at least one cross-member connected to respective intermediate portions of the beams.

The invention claimed is: 
     
       1. A bed for a coordinate measuring machine comprising:
 a frame provided with a pair of parallel beams spaced apart from one another; 
 bearing guide means for a mobile unit of the machine; and 
 a workpiece table at least partially housed between the beams, the workpiece table and the frame being constrained to one another by constraint means that decouple the deformations thereof, wherein the frame comprises at least one cross-member connected to respective intermediate portions of the beams. 
 
     
     
       2. The bed according to  claim 1 , wherein the beams rest on the cross-member. 
     
     
       3. The bed according to  claim 1 , wherein the frame rests on three supports and in that the constraint means are set on the vertical of said supports. 
     
     
       4. The bed according to  claim 3 , wherein the bed comprises two cross-members, a first support and a second support being set underneath the cross-members in the proximity of the respective beams, a third support being set underneath the other cross-member in the centre thereof. 
     
     
       5. The bed according to  claim 4 , wherein the two cross-members are parallel to one another. 
     
     
       6. The bed according to  claim 3 , wherein the constraint means are of isostatic type. 
     
     
       7. The bed according to  claim 3 , wherein the translations between the workpiece table and the frame due to the deformations are negligible, wherein said constraint means define a statically indeterminate constraint system that eliminates the translation degrees of freedom. 
     
     
       8. The bed according to  claim 1 , wherein the bed comprises a single cross-member, a first support and a second support being set underneath the beams, a third support being set underneath the cross-member in the proximity of the other beam. 
     
     
       9. The bed according to  claim 8 , wherein the first and second supports comprise a resting foot and a bracket set between the resting foot and the frame; the bracket of said first and second supports comprising a first portion fixed to the beam and a portion projecting from the beam towards the inside of the frame; the resting foot being set underneath the second portion of the bracket. 
     
     
       10. The bed according to  claim 1 , wherein said workpiece table is made at least prevalently of a pourable material. 
     
     
       11. The bed according to  claim 10 , wherein said material is a non-metallic material. 
     
     
       12. The bed according to  claim 11 , wherein said material is concrete. 
     
     
       13. The bed according to  claim 12 , wherein said second material is granite. 
     
     
       14. The bed according to  claim 12 , wherein said second material is a ceramic material. 
     
     
       15. The bed according to  claim 1 , wherein the bed comprises a top layer made of a second material and defining a working surface of the machine.